JPH01205093A - Coloring method for aluminum or aluminum alloy - Google Patents

Abstract

PURPOSE:To form a desired colored film having many variations by reanodizing an anodized film formed on the surface of Al to expand the pore diameter of the film, then depositing a metal oxide in the pores by an electrophoresis method. CONSTITUTION:The surface of the Al or Al alloy is anodized to form the anodized film 1 having the alumite pores 2. The film is then reanodized in an acidic or alkaline soln. to expand 2a the diameter of the pores 2 to about >=300Angstrom . The anodized film 1a expanded in the pore diameter is subjected to electrophoresis in a hydrosol of a metal such as Fe, Cr, Co, Mn, Ni, Cu or Ag the oxide (hydrous oxide) of which is chromatic. The granular metal oxide 5 or laminar metal oxide 6 is deposited in the alumite pores (micropores) of the film 1a by this treatment. The selection of the color tone of the film from a wide range of hues is thereby enabled and the product having high versatility is obtd.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention provides aluminum or aluminum alloy products,
For example, architectural products such as aluminum sashes, sliding doors, entrances, etc.
Showcases, daily necessities, stepladders, ladders, decorative items, castings,
This invention relates to a method for coloring aluminum or aluminum alloy used in die casting, parts for vehicles, ships, etc.

(Prior art) With the diversification of consumer lifestyles and demand preferences in recent years, aluminum and aluminum alloy products have become available in a variety of colors, particularly red, yellow, and blue, as well as various intermediate colors thereof, and even Basdell colors. (opaque color) is now required.

The conventional electrolytic coloring method involves forming an anodic oxide film on aluminum or aluminum alloy, electrolyzing it in an aqueous metal salt solution to deposit metal within the anodic oxide film, and coloring using the resulting reflection and absorption of light. A secondary electrolysis method is adopted.

(Problems to be Solved by the Invention) According to the above-mentioned conventional method, the coloring is mainly caused by the effect of the precipitated metal itself, so the range of coloring modes is small;
It is not possible to adequately respond to the recent diversification of demand preferences. In addition, in order to solve such problems, a special application
92590 (Japanese Unexamined Patent Publication No. 62-151595),
Anodic oxide film compositions for aluminum and aluminum alloys! ! ! The J construction method has been proposed. However, in this method, the oxide cannot be sufficiently precipitated because the diameter of the small pores formed in the positive IkM coating is small.

(Means for Solving the Problems) As a result of research into a method for solving the above-mentioned problems when coating aluminum or aluminum alloy with color, the present inventor carried out a treatment to enlarge the diameter of alumite pores (micropores), and then They discovered that it is extremely effective to precipitate the metal oxide (hydrous oxide) into the alumite pores of the film by electrophoresis in a colored metal hydrosol, and completed the present invention. reached.

That is, the present invention forms an anodic oxide film on aluminum or an aluminum alloy, and recycles the film in an acidic solution such as sulfuric acid, phosphoric acid, or oxalic acid, or in an alkaline solution such as sodium hydroxide, trisodium phosphate, or sodium carbonate. After performing anodizing treatment to enlarge the pore size of the anodic oxide film, Fe, Or.

Precipitating metal oxides (hydrous oxides) into the micropores of the film by electrophoresis in a hydrosol of metals whose oxides (hydrated oxides) are colored, such as co, Mn, N + , CLJ, AQ, etc. This is a method for coloring aluminum or an aluminum alloy, characterized in that the color tone is unique to the metal oxide (hydrous oxide).

Hydrosol as used herein refers to particles in the polynuclear complex ion-colloidal state. A polynuclear complex ion is an ion in which a mononuclear complex ion forms a surface with OH- as a Funahashi element (referred to as olization) and has a high molecular weight.

(Description of Means) (1) In order to form an anodic oxide film on aluminum or an aluminum alloy, a normal anodic oxidation method is employed. For example, inorganic acids such as sulfuric acid, phosphoric acid, phosphoric acid, isoic acid such as oxalic acid, sulfosalicylic acid, malonic acid, sodium hydroxide, tris-1-lyulium phosphate, etc.
' In an aqueous solution consisting of 8, direct current, alternating current, pulse, 1] 1
<Anodic oxide film is formed by electrolysis using wave or AC/DC superposition method. As a result, an anodic oxide film 1 having alumite holes 2 as shown in FIG. 1 is obtained. In addition, in FIGS. 1 to 4, 3 is a base material, and 4 is a barrier layer.

The above-mentioned method for enlarging the pore size includes, for example, using a sample as an anode in an inorganic acid and applying direct current, pulses, or alternating current, or immersing the sample in an inorganic acid. As a result, enlarged alumite holes 2a as shown in FIG. 2 can be obtained. Note that the diameter a of the alumite hole 2a is preferably expanded to about 300 mm or more.

The anodic oxide film 1a with the enlarged pore size is coated with Fe, Cr.
, Go, Mn, Ni, Cu, Ao, etc., by electrophoresis in a hydrosol of a metal whose oxide (hydrous oxide) is colored as shown in FIG. A granular metal oxide 5 or a layered metal oxide 6 as shown in FIG. 4 can be deposited.

Examples of the metal oxides include Fe, Cr, Co,
Colored materials such as Mn, N i , Cu, and Δq are used. Moreover, the metal oxide herein includes a hydrated metal oxide, and the term "colored" means an achromatic color excluding chromatic colors and white.

Depending on the required color tone, various metals may be used alone or in combination. In the present invention, since a metal oxide hydrosol is used as described later, the unique coloring is caused by the metal oxide rather than the metal itself.

(2) Hydrosols of the above metals, such as Fe, C
sulfates of r, Co, Mn, Ni, CLJ, AQ, etc.
Inorganic salts such as nitrates and ammonium salts, and oxalic acid,
A hydrosol of a metal oxide (hydrous oxide) with a diameter of 300 A or less is obtained by adding a basic aqueous solution such as sodium carbonate, sodium hydroxide, or ammonium hydroxide to an aqueous solution of at least one organic salt such as tartaric acid. It will be done.

As a method for preparing the above-mentioned hydrosol, a method of adding a basic aqueous solution to an aqueous metal salt solution is adopted. For example; a. In a hydrosol of iron oxide, 1 mol/fJ of Fe
Add 1 m to 250 ml of (NO3)3 aqueous solution while stirring,
25mol/41 Na2CO3 aqueous solution at about 20IR
Add at a rate of I/min until the pH reaches 2.5 and leave for 30 minutes with stirring to obtain a transparent hydrosol of hydrated iron oxide.

b. In the hydrosol of M-Rom, Q, 4m01
/E Cr2 (SO4)3 aqueous solution 5001 0°4m
About 20ml/l1in of o1/1 Na2CO3 aqueous solution
until the pH reaches 3.0 to obtain a transparent hydrosol of hydrated chromium oxide.

c, 0.5 mol for cobalt illumination hydrosol
, Q, 5m to 100n+l of CO3O4 aqueous solution of Jl.

+/41 Na2CO3 aqueous solution at approximately 10ml/min
(7) Add at a rate until the pH reaches 3.2 to obtain a cobalt oxide hydrosol.

(3) As the above-mentioned electrophoresis method, for example, a method is employed in which a direct current or pulse voltage is applied using the film as a cathode, or an alternating current voltage is applied.

As the energization waveform used in the above-mentioned electrophoresis method in a hydrosol, the methods shown in FIGS. 5 to 7, for example, are employed.

FIG. 5 shows an example of applying a DC voltage, FIG. 6 shows an example of applying a pulse voltage, and FIG. 7 shows an example of applying an AC voltage. Note that the present invention is not limited to the above method, and any method may be employed as long as it electrophoresizes gold [monide] in a hydrosol. (4) If necessary, a method may be adopted in which, for example, after coloring treatment, washing with water or the like is performed, and then heat treatment is performed on the colored film at 120 to 200°C. By performing this heat treatment, the hydroxide contained in the granular gold aR oxide 5 (FIG. 3) or the layered metal oxide 6 (FIG. 4) is removed, and a new color tone can be obtained.

[First Example] ■ Pure aluminum (JIS designation: Δ1100P-H2
4) was anodized by a conventional method in a 17 wt % sulfuric acid bath to obtain an anodic oxide film with a thickness of 10 μm.

■ Using the film as an anode and carbon as a counter electrode, phosphoric acid 1
A DC voltage of 10 V was applied for 10 minutes in a 0 vt% bath to enlarge the pore diameter.

■ After washing with water, the skin was used as a cathode and the stainless steel as an anode. A voltage V1=14V was applied. The relationship between the obtained color tone and the application time t1 is as follows.

[Second Example] ■ Pure aluminum (JIS designation: A1200P-H1
4) was subjected to anodic oxidation treatment in a 17 wt % sulfuric acid bath by a conventional method to obtain an anodic oxidation film having a thickness of 10 μm.

■ Using the film as an anode and carbon as a counter electrode, phosphorus 11
A DC voltage of 10 V was applied for 10 minutes in a 0 wt % bath to enlarge the pore diameter.

■ The film was used as a cathode and carbon was used as an anode in an aqueous solution of 0.05 M cobalt sulfate ammonium hexahydrate adjusted to DH8.02 with ammonium hydroxide. 2 = 2 seconds, at rest 1ift L 2-1 seconds) V2 = 12V was applied. 1! ? The relationship between the applied color tone and the application time t3 is as follows.

(2) The film was further heat-treated at 150° C. for 2 hours using an electric furnace to obtain a gray film.

Third Example] ■ Corrosion-resistant aluminum alloy (JIS designation: A60638
-T5) was anodized in a 3 wt% oxalic acid bath by a conventional method to form a golden anodic oxide film with a thickness of 6 μm (
It was.

(2) Using the film as an anode and carbon as a counter electrode, a DC voltage of 15 V was applied for 5 minutes in a 10 w% trisodium phosphate bath to enlarge the pore diameter.

■ After washing with water, purge the film with sodium hydroxide.
In an aqueous solution of 0.5 M nickel sulfate hexahydrate adjusted to H5.80, an alternating current voltage V3 = 18 V as shown in FIG. 7 was applied for an application time t3 = 5 minutes using nickel as a counter electrode.

The resulting color tone was dark gray.

(Effects of the Invention) As explained above, according to the present invention, after forming the positive ff1M coating, the diameter of the alumite hole 2 is enlarged, so that the diameter of the alumite hole 2a can be increased as shown in FIG. a is enlarged to about 3008, and the granular metal oxide 5 shown in FIG. 3 or the layered metal oxide 6 shown in FIG.
is more likely to be precipitated. Therefore, the metal oxide precipitated5.
6 is firmly and sufficiently precipitated in the alumite holes 2a, and it is possible to obtain a coating with a wide variety of colors, thereby making it possible to provide a product that can fully meet the diversification of demand and preferences in recent years.

Furthermore, by enlarging the pore diameter, it is possible to deposit granular metal oxide 5 or layered metal oxide 6 in the alumite pores 2a, so that the current application time during electrophoresis is slightly changed. A desired color tone can be selected from a wide range of hues (for example, from light yellow to reddish brown). Therefore, from this point of view as well, it is possible to obtain a coating with a wide variety of colors, making it possible to manufacture products that match the preferences of many consumers.

The present invention employs a method in which metal oxides (hydrated oxides) are deposited in the micropores of the film by electrophoresis in a hydrosol, so durability is very good compared to conventional methods of depositing metals. becomes. For example, Cr
When a salt bath is used, properties unique to metal oxides (hydrous oxides) are imparted, such as improved abrasion resistance of the film.

In addition, since the metal oxide of the hydrosol in the present invention also contains hydroxide, when heat treatment is performed as necessary, the metal oxide 5 becomes particulate and the metal oxide 6 forms a layer. The hydroxides contained in it are removed and the new <> (!!
, you can get the key. Therefore, it is possible to select the color tone of the colored film from a wider range of hues (for example, colors ranging from pale yellow to green). Therefore, a highly versatile product can be provided.

[Brief explanation of the drawing]

Figure 1 is a schematic cross-sectional view of an anodic oxide film with alumite holes, Figure 2 is a cross-sectional view of an anodized film showing enlarged alumite holes, and Figure 3 is a schematic cross-sectional view of an anodic oxide film with enlarged alumite holes. A schematic cross-sectional view of an anodized film showing a state in which oxides (hydrous oxides) have been precipitated. Figure 4 shows a state in which layered metal oxides (hydrous oxides) have been deposited in enlarged alumite pores. The schematic cross-sectional views of the anodic oxide film and FIGS. 5 to 7 are diagrams showing a voltage application method that can be employed in electrophoresis of the present invention. Patent applicant: Japan Aluminum Industry Co., Ltd. Agent: Patent attorney: Tadataka Oshiki i,':,"4'l:'! ',',
,:'iFigure 1Figure 2Figure 3Figure 5Figure 6Figure 7

Claims (1)

[Claims] 1. An anodic oxide film is formed on aluminum or an aluminum alloy, and the film is coated with an acidic solution such as sulfuric acid, phosphoric acid, or oxalic acid, or an alkaline solution such as sodium hydroxide, trisodium phosphate, or sodium carbonate. After enlarging the pore size of the anodic oxide film by re-anodizing in the
The metal oxide (hydrous oxide) is precipitated into the micropores of the film by electrophoresis in a hydrosol of a metal whose oxide (hydrous oxide) is colored, such as r, Co, Mn, Ni, Cu, Ag. A method for coloring aluminum or an aluminum alloy, characterized in that the coloring is performed in a color tone unique to the metal oxide (hydrous oxide). 2. Fe, Cr, Co, Mn as metal hydrosols
Sodium carbonate, sodium hydroxide, ammonium hydroxide, etc. are added to an aqueous solution of at least one of inorganic salts such as sulfates, nitrates, and ammonium salts such as Ni, Cu, and Ag, and organic salts such as oxalic acid and tartaric acid. 2. The method for coloring aluminum or aluminum alloy according to claim 1, wherein a hydrosol of a metal oxide (hydrous oxide) having a diameter of 300 Å or less is used by adding a basic aqueous solution of . 3. The method for coloring aluminum or aluminum alloy according to claim 1, wherein the electrophoresis method is carried out by applying a direct current or pulse voltage or applying an alternating current voltage using the film as a cathode. 4.After coloring treatment, after washing with water etc., apply 1 to the colored film.
The method for coloring aluminum or an aluminum alloy according to claim 1, wherein a heat treatment is performed at 20 to 300°C.